Long-Range Vga Image Transmission System Providing Automatic Image Adjustment

1. A long-range VGA image transmission system providing automatic image adjustment, comprising: an image output source for providing a first image signal; a test circuit for providing a test signal; an image encoding and transmitting circuit being electrically connected to the image output source and the test circuit for receiving the first image signal and the test signal to generate a transmission signal through encoding; an image decoding and receiving circuit being composed of an RGB time comparison circuit, an image sharpness detection circuit, and an image brightness detection circuit, and electrically connected to the image encoding and transmitting circuit for receiving and decoding the transmission signal to generate a second image signal and the test signal; an image-enhancement compensation circuit being electrically connected to the image decoding and receiving circuit for receiving and transmitting the second image signal and the test signal; an image detection and comparison circuit being electrically connected to the image-enhancement compensation circuit for receiving the second image signal and the test signal, and detecting and comparing the second image signal with the test signal to generate an adjustment signal; and an image display device being electrically connected to the image-enhancement compensation circuit for receiving the second image signal; wherein the image-enhancement compensation circuit receives the adjustment signal and then automatically adjusts the second image signal to generate a third image signal; and the image display device starts receiving the third image signal after the adjustment made by the image detection and comparison circuit, and displays an image based on the third image signal.

2. The long-range VGA image transmission system providing automatic image adjustment as claimed in claim 1 , wherein the RGB time comparison circuit detects any time delay among three primary light colors of RGB of the second image signal, and uses one of the primary light colors that has a largest time delay as a reference to control and increase delay signals to the other two leading primary light colors until there is not any time delay among the three primary light colors.

3. The long-range VGA image transmission system providing automatic image adjustment as claimed in claim 1 , wherein the image sharpness detection circuit detects and determines according to a detection result whether a sharpness of the second image signal needs to be decreased or increased; and wherein, when it is determined the image sharpness needs to be decreased, the image sharpness detection circuit first sets an image sharpness compensation control signal to a highest value thereof and then decreases the compensation signal step by step until the detection result changes; and wherein, when it is determined the image sharpness needs to be increased, the image sharpness detection circuit first sets the image sharpness compensation control signal to a lowest value thereof and then increases the compensation signal step by step until the detection result changes.

4. The long-range VGA image transmission system providing automatic image adjustment as claimed in claim 1 , wherein the image brightness detection circuit detects for a target voltage value of the second image signal; and wherein, when a measured voltage value is lower than the target voltage value, the image brightness detection circuit first sets a gain compensation signal to a smallest value thereof and then increases the compensation signal step by step until the detected voltage value changes; and wherein, when a measured voltage is higher than the target voltage value, the image brightness detection circuit first sets the gain compensation signal to a largest value thereof and then decreases the compensation signal step by step until the detected voltage value changes.

5. The long-range VGA image transmission system providing automatic image adjustment as claimed in claim 1 , wherein the adjustment signal is composed of an RGB compensation signal, an image sharpness compensation signal, and a gain compensation signal.

6. The long-range VGA image transmission system providing automatic image adjustment as claimed in claim 1 , wherein the first image signal has multiple visible zones spaced alternately with multiple invisible zones; and the image encoding and transmitting circuit adding the test signal to the invisible zones of the first image signal.

7. The long-range VGA image transmission system providing automatic image adjustment as claimed in claim 1 , wherein the image encoding and transmitting circuit and the image decoding and receiving circuit are electrically connected to each other via a twisted pair cable.

8. The long-range VGA image transmission system providing automatic image adjustment as claimed in claim 7 , wherein the twisted pair cable is selected from the group consisting of a CAT5 cable, a CAT5E cable, and a CAT6 cable.

9. A long-range VGA image transmission system providing automatic image adjustment, comprising: an image output source for providing a first image signal, the first image signal has multiple visible zones spaced alternately with multiple invisible zones; a test circuit for providing a test signal; an image encoding and transmitting circuit being electrically connected to the image output source and the test circuit for receiving the first image signal and the test signal, adding the test signal to the invisible zones of the first image signal to generate a transmission signal through encoding; an image decoding and receiving circuit being electrically connected to the image encoding and transmitting circuit for receiving and decoding the transmission signal to generate a second image signal and the test signal; an image-enhancement compensation circuit being electrically connected to the image decoding and receiving circuit for receiving and transmitting the second image signal and the test signal; an image detection and comparison circuit being electrically connected to the image-enhancement compensation circuit for receiving the second image signal and the test signal, and detecting and comparing the second image signal with the test signal to generate an adjustment signal; and an image display device being electrically connected to the image-enhancement compensation circuit for receiving the second image signal; wherein the image-enhancement compensation circuit receives the adjustment signal and then automatically adjusts the second image signal to generate a third image signal; and the image display device starts receiving the third image signal after the adjustment made by the image detection and comparison circuit, and displays an image based on the third image signal.

10. The long-range VGA image transmission system providing automatic image adjustment as claimed in claim 9 , wherein the image detection and comparison circuit is composed of an RGB time comparison circuit, an image sharpness detection circuit, and an image brightness detection circuit.

11. The long-range VGA image transmission system providing automatic image adjustment as claimed in claim 10 , wherein the RGB time comparison circuit detects any time delay among three primary light colors of RGB of the second image signal, and uses one of the primary light colors that has a largest time delay as a reference to control and increase delay signals to the other two leading primary light colors until there is not any time delay among the three primary light colors.

12. The long-range VGA image transmission system providing automatic image adjustment as claimed in claim 10 , wherein the image sharpness detection circuit detects and determines according to a detection result whether a sharpness of the second image signal needs to be decreased or increased; and wherein, when it is determined the image sharpness needs to be decreased, the image sharpness detection circuit first sets an image sharpness compensation control signal to a highest value thereof and then decreases the compensation signal step by step until the detection result changes; and wherein, when it is determined the image sharpness needs to be increased, the image sharpness detection circuit first sets the image sharpness compensation control signal to a lowest value thereof and then increases the compensation signal step by step until the detection result changes.

13. The long-range VGA image transmission system providing automatic image adjustment as claimed in claim 10 , wherein the image brightness detection circuit detects for a target voltage value of the second image signal; and wherein, when a measured voltage value is lower than the target voltage value, the image brightness detection circuit first sets a gain compensation signal to a smallest value thereof and then increases the compensation signal step by step until the detected voltage value changes; and wherein, when a measured voltage is higher than the target voltage value, the image brightness detection circuit first sets the gain compensation signal to a largest value thereof and then decreases the compensation signal step by step until the detected voltage value changes.

14. The long-range VGA image transmission system providing automatic image adjustment as claimed in claim 10 , wherein the adjustment signal is composed of an RGB compensation signal, an image sharpness compensation signal, and a gain compensation signal.

15. The long-range VGA image transmission system providing automatic image adjustment as claimed in claim 9 , wherein the image encoding and transmitting circuit and the image decoding and receiving circuit are electrically connected to each other via a twisted pair cable.

16. The long-range VGA image transmission system providing automatic image adjustment as claimed in claim 15 , wherein the twisted pair cable is selected from the group consisting of a CAT5 cable, a CAT5E cable, and a CAT6 cable.